1. Field of the Invention
The present invention relates to a record condition extraction system for and a record condition extraction method of obtaining an optimum record condition of a dielectric recording medium which records information in a microdomain of a dielectric substance with high density, as well as an information recording apparatus.
2. Description of the Related Art
Recently, many types of dielectric materials and piezoelectric materials have been developed, and most of them are used for ultrasonic elements, optical elements, a memory, and the like. In accordance with the fact, a method of measuring a remanent polarization distribution of the dielectric material and local anisotropy of the piezoelectric material has been developed. Also, by using this technique, another technique of recording information in the dielectric material and reproducing the information has been developed.
Conventionally, in order to observe a polarization domain of the dielectric substance, there is a method of using the difference of etching rates in a plane direction by chemical etching. However, only resolution on the order of μm can be expected in this method, and it requires time because of the need to pass through processes of the chemical etching and the like until the actual observation. With respect to the microdomain, there is a method of applying a high-frequency voltage to the dielectric material with an AFM (Atomic Force Microscope) apparatus and using piezoelectric response at that time. In this method, however, it is difficult to obtain a detection signal having enough S/N ratios to the microdomain on the order of nm.
The inventors of the present invention have developed a SNDM (Scanning Nonlinear Dielectric Microscopy) to form and observe the microdomain. This apparatus can observe the polarization domain of the dielectric substance on the order of Å and form an artificial polarization domain by the application of an electric field to the dielectric substance. However, there is hardly any concrete condition extraction method of forming with good reproducibility a micro polarization domain that has a stable level for recording and reproducing.
If the polarization domain is formed in the dielectric material and this is recorded as information, it is necessary to partially align the polarization of the dielectric substance with the direction of an outer electric field by applying, from outside, the electric field whose intensity is stronger than that of the coercive electric field of the dielectric material. The inventors of the present invention have formed the microdomains on the order of sub μm to PZT film and LiTaO3 crystal using the above described SNDM, but they are not sufficiently stable. At the same time, few researchers report the technique on the formation of a stable sub μm microdomain, which is appropriate for recording and reproducing with high recording density to the dielectric material, in the current situation.